The present invention relates to a cassette loading device for cassette-type video tape recorders (hereinafter referred to as "VTR") by which a tape cassette inserted into the main body of the VTR is transported to the specified loaded position for reproduction and recording.
Generally used as cassette loading devices in recent years are those of the so-called front loading type by which the cassette is inserted into a casette holder in the interior of the main body of VTR through a cassette inlet which is open at the front side of the VTR main body. The present invention relates to improvements in such front loading type.
With reference to FIG. 11 showing a cassette loading device of the front loading type, a cassette 100 is inserted through a cassette inlet 16 at the front side of the main body 101 of a VTR into a cassette holder 6 at an insertion standby position A within the VTR main body. By means of a drive source, i.e. a drive motor 5, and a gear assembly or like power transmission mechanism 103 coupled to the motor, the cassette is transported along with the cassette holder 6 to a loaded position B horizontally and vertically as indicated by the arrows. When the cassette 100 is set in this position, the tape is withdrawn and wound around a VTR cylinder 102 by a tape loading mechanism (not shown) for recording or reproduction.
Such a cassette loading device of the front loading type is disclosed in detail, for example, in Published Unexamined Japanese Patent Application SHO No. 58-164049.
With the cassette loading device described above, the cassette is being placed into the cassette holder 6 at the insertion standby position A and pushed inwardly of the device manually. The command for initiating the drive source into operation is then given on the way to go in by turning on a switch provided in the VTR main body.
The drive force delivered from the drive motor 5 through the power transmission mechanism 103 is utilized for holding the cassette 100 in the loaded position B stably. The power transmission mechanism includes, for example, a cam mechanism (not shown) which is coupled to the drive motor. When the cassette holder approaches the loaded position, the cam face of the cam mechanism moves with the rotation of the drive motor, whereby the cassette holder 6 pushed inwardly of the device is pressed down against the chassis of the VTR main body 101 by a cam follower. In this state, the drive motor is de-energized. When the cassette is completely loaded in position, the cam follower is positioned at the top of the cam face, where the follower is dynamically in balance with the cam. Consequently, even if the drive motor is de-energized, the cassette holder 6 is held pressed down, so that the holder, i.e. the cassette 100 can be restrained in place on the chassis without backlash.
To restrain the cassette holder with an increased force when the cassette is completely loaded in place, there is a need to increase the load on the cam mechanism to increase the pressure of the cam face on the cam follower. However, this requires a greater power for driving the cam face, and for this purpose, the power transmission mechanism is conventionally set to a higher reduction ratio.
Accordingly, the conventional cassette loading device has the problem that owing to the increase in the reduction ratio, a greater pressure is required for reversely driving the power transmission mechanism from the output side, i.e. from the cassette holder side, when the cassette holder is pushed in until the drive motor is automatically brought into operation.